Finding fault in a shear zone: a magnetic and drill core study in the Valentine Lake Property, Newfoundland, Canada
DOI:
https://doi.org/10.4138/atlgeo.2023.008Abstract
The Valentine Lake Property in southwestern Newfoundland has five known gold deposits over a distance of 20 km along a northeast to southwest trend and is expected to be the future site for the largest gold mine in Atlantic Canada. The property contains structurally controlled orogenic-type quartz-tourmaline-pyrite veins, which are gold-bearing, occurring along or proximal to the Valentine Lake Shear Zone. The mineralization is found mostly on the northwest side of the shear zone in intrusive rocks and is rare in the conglomerate on the southeast side. The area has many mafic dykes, which show up well when conducting a magnetic survey due to their magnetite content. These dykes, like the mineralization, occur mainly in the intrusive rocks and trend predominantly subparallel to the shear zone, and so can help indicate structure. To constrain the location of the shear zone (and hence the mineralized region) in an area where an offset was suspected, a detailed magnetic survey was conducted over a 200 m x 300 m grid comprising sixteen lines. With the collected data, residual magnetic intensity maps were created and processed. A region was identified where the pattern of linear magnetic highs weaken and appear to terminate near the suspected offset. In combination with drill core information, this location is interpreted as a fault offset of the shear zone. The loss in magnetic intensity is possibly due to alteration or thinning of the mafic dykes near the fault.
References
Dentith, M. and Mudge, S.T. 2014. Geophysics for the mineral exploration geoscientist. Cambridge University Press, 438 p. https://doi.org/10.1017/CBO9781139024358
Evans, D.T.W. and Kean, B.F. 2002. The Victoria Lake Supergroup, central Newfoundland – its definition, setting and volcanogenic massive sulphide mineralization. Newfoundland and Labrador Department of Mines and Energy, Geological Survey. Open File NFLD/2790, 68 p.
Evans, D.T.W., Kean, B.F., and Dunning, G.R. 1990. Geological studies, Victoria Lake Group, central Newfoundland. In Current Research, Newfoundland Department of Mines and Energy, Geological Survey Branch, Report 90-1, pp. 135–144.
Flanagan, M. 2021. Magnetics study within the Valentine Gold Property, Newfoundland. Unpublished B.Sc. Honours thesis, Memorial University of Newfoundland and Labrador, St. John’s, Newfoundland and Labrador, Canada 73 p.
Geomagnetism Canada 2020. Magnetic declination calculator. URL <https://www.geomag.nrcan.gc.ca/calc/calc-en.php> 14 October 2020.
Guay, M., Riopel, J., Carrier, A., Dunsworth, S., Allou, B., Trudel, D., St-Jean, E., D’Amours, I., and Letourneau, O. 2007. Helicopter-borne magnetic, gamma-ray spectrometry and VLF geophysical survey NTS map sheets 12A/06 and 12A/07. Unpublished data acquisition report, Valentine Lake gold project, 377 p. URL <https://gis.geosurv.gov.nl.ca/geofilePDFS/ReceivedBatch46/012A_1447_Part2.pdf> 08 July 2021.
Honsberger, I.W., Bleeker, W., Kamo, S.L., Sandeman, H.A.I., Evans, D.T.W., Rogers, N., van Staal, C.R., and Dunning, G.R. 2022. Latest Silurian syntectonic sedimentation and magmatism and Early Devonian orogenic gold mineralization, central Newfoundland Appalachians, Canada: Setting, structure, lithogeochemistry, and high-precision U-Pb geochronology. Geological Society of America Bulletin, 134, pp. 2933–2957. https://doi.org/10.1130/B36083.1
Kruse, S. 2020. Structural analysis of the Valentine Gold Project. Marathon Gold Corp., Unpublished internal report Project#: 20-46-F. Terrane Geoscience. 46 p.
Marathon Gold 2021. Technical report & feasibility study on the Valentine Gold Project. URL <https://marathon-gold.com/site/uploads/2021/04/Valentine-Gold-43-101_FS-Report_FINAL_Apr23_R2.pdf> 08 July 2021
Marathon Gold 2022. Valentine Gold Project, deposits. URL <https://marathon-gold.com/valentine-gold-project/deposits/> 1 February 2022.
Melanson, D. and Parks, C. 2019. Marathon Gold: Valentine Mine. Final Report on Lidar Survey. Aethon Aerial Solutions, Burlington, ON. Marathon Gold unpublished internal report, 10 p.
Runyon, S.E., Seedorff, E., Barton, M.D., Steele-MacInnis, M., Lecumberri-Sanchez, P., and Mazdab, F.K. 2019. Coarse muscovite veins and alteration in porphyry systems, Ore Geology Reviews 113, pp. 1–32. https://doi.org/10.1016/j.oregeorev.2019.103045
Szitkar, F., Dyment, J., Choi, Y., and Fouquet, Y. 2014. What causes low magnetization at basalt-hosted hydrothermal sites? Insights from inactive site Krasnov (MAR 16°38′N). Geochemistry, Geophysics, Geosystems 15, pp. 1441–1451. https://doi.org/10.1002/2014GC005284
Terraplus. 2020. Magnetic Susceptibility Meters URL <https://terraplus.ca/product-details/magnetic-susceptibility-meters> 24 September 2020.
Tettelaar, T. and Dunsworth, S. 2015. Supplementary assessment report of diamond core drilling, prospecting, trenching, channel sampling, trench rehabilitation, geological trench mapping, line cutting, ground magnetometer survey, environmental studies, and road repair & maintenance, Valentine Lake Property, Central Newfoundland, NTS 12A/06. Unpublished data acquisition report, 981 p. URL <https://gis.geosurv.gov.nl.ca/geofilePDFS/Batch2019/012A_1761.pdf> 24 September 2020.
Tettelaar, T. and Dunsworth, S. 2016. Supplementary assessment report of diamond core drilling, line cutting, ground magnetometer survey, and road repair & maintenance, Valentine Lake Property, Central Newfoundland, NTS 12A/06. Unpublished data acquisition report, 160 p. URL <https://gis.geosurv.gov.nl.ca/geofilePDFS/Batch2019/012A_1805.pdf> 24 September 2020.
Valverde-Vaquero, P., and van Staal, C.R. 2002. Geology and magnetic anomalies of the Exploits–Meelpaeg boundary zone in the Victoria Lake area (central Newfoundland): regional implications. Newfoundland Department of Mines and Energy Geological Survey, Report 02-1, pp. 197–209.
Van Staal, C. and Valverde-Vaquero, P. 2001. Relationships between the Dunnage-Gander zones in the Victoria Lake-Peter Strides Pond area. Newfoundland Department of Mines and Energy Geological Survey, Report 2001-1, pp. 1–9.
Van Staal, C., Valverde-Vaquero, P., Zagorevski, A., Rogers, N., Lissenberg, C., McNicoll, V. 2005. Geology, Victoria Lake, Newfoundland and Labrador. Geological Survey of Canada, Open File 1667, scale 1:50 000. https://doi.org/10.4095/221287
Van Staal, C.R., Whalen, J.B., Valverde-Vaquero, P., Zagorevski, A., and Rogers, N. 2009. Pre-Carboniferous, episodic accretion-related, orogenesis along the Laurentian margin of the northern Appalachians. Geological Society, London, Special Publications, 327, pp. 271–316. https://doi.10.1144/SP327.13
White, S.E. and Waldron, J.W.F. 2022. Along-strike variations in the deformed Laurentian margin in the Northern Appalachians: Role of inherited margin geometry and colliding arcs, Earth Science Reviews 226. https://doi.org/10.1016/j.earscirev.2022.103931
Williams, H. 1979. Appalachian Orogen in Canada. Canadian Journal of Earth Sciences, 16, pp. 792–807. https://doi.org/10.1139/e79-070
Williams, H., Colman-Sadd, S.P., and Swinden, H.S. 1988. Tectonic-stratigraphic subdivisions of central Newfoundland. In Current Research, Part B, Geological Survey of Canada, Paper 88-JB, pp. 91–98. https://doi.org/10.4095/122425
Downloads
Published
How to Cite
Issue
Section
License
As of January 1, 2025, Atlantic Geoscience is adopting Creative Commons Attribution 4.0 International (CC BY 4.0) This license requires that re-users give credit to the creator. It allows re-users to distribute, remix, adapt, and build upon the material in any medium or format, even for commercial purposes.
Copyright to material published in Atlantic Geoscience is normally retained by the author. Alternate arrangements can be made on request for government employees.
Permission to use a single graphic for which the author owns copyright is considered “fair dealing” under the Canadian Copyright Act and “fair use” by the journal, and no other permission need be granted, subject to the image being appropriately cited in all reproductions. The same fair dealing/fair use policy applies to sections of text up to 100 words in length.
